LCD and LED refer to two separate parts of the projector.
The backlight is usually LED or a lamp. LEDs last longer and don't require any replacements. They're also smaller than lamps. My understanding is that LEDs are not as bright as proper lamps but I think the newest LEDs are just as good.
As for the image forming bit, you have either LCD or DLP. LCD is better for presentation and whatnots whereas DLP is better for movies and cinema type stuff. Your millage for each may vary and it really depends on what and where you're going to be projecting.